The oldest Confederate volcano tells all

TIL: There is an extinct volcano sitting directly beneath the city of Jackson, Mississippi. Specifically, it is approximately a half mile below the Mississippi Colosseum and state fairgrounds. In the late Cretaceous period — about 100 million years ago — this part of North America was under water. In fact, "North America" back then was actually more like a couple of mini-continents surrounded by ocean. The Jackson Volcano was the heart of a 400-square-mile island in that sea. It hasn't erupted in 65 million years, but the ground is still hot enough that some local wells pump up 102°F water. [Edited to add that the relationship between groundwater temp and the Jackson Volcano may not be accurate. Eric Klemetti — geoscientist and Wired blogger — told me he would be surprised if an extinct volcano was the source of that heat.]

Does Eric Klemetti have an explanation for the natural hot water, then? I’m curious, in part because after reading The Road, and figuring out that one way to survive such a catastrophe (which is never fully explained by Cormac McCarthy, but one theory is that the overcast skies and reduced temperature are due to (ironically) an explosion of the Yellowstone supercaldera) would be to build a house/compound that gets its energy from a geothermal source, which could be used to generate electricity to grow food in hydroponic gardens underground.